What does this actually mean for the climate and for the damage that climate change might bring?

Running the agreements through the PAGE09 integrated assessment model, and throwing in the EU’s pledge to cut emissions by 40% by 2030 for good measure, it appears that these agreements on their own give us less than a 1% chance of keeping the rise in global mean temperatures below the iconic 2 degC level in 2100. Most likely the rise will be about 3.8 degC . This assumes all other regions of the world continue to allow their emissions to grow along the IPCC’s A1B business as usual scenario. Annual mean climate change impacts will still rise to about $20 trillion per year by 2100, with about 2/3 of those impacts in poor countries.

So while the deal may be politically important, statements about its ambition should be treated with caution.

Update added 12:20 on 12 November 2014: Some have commented that assuming the rest of the world continues on the A1B business as usual path is unduly pessimistic. So I have repeated the analysis assuming the rest of the OECD matches the US’s actions of a 28% cut by 2025 (with the EU cutting by 40% as before), and the rest of the developing world matches China’s pledge to stop increasing emissions by 2030. The chance of staying below 2degC in 2100 rises to 1.1%, and the mean impacts in 2100 are now about $19 trillion. The underlying message remains the same: These pledges are only the first step on a very long road.

24 Responses to The US China climate deal – don’t get carried away

Debates about climate change should begin with per-capita emissions figures. China now sits at 7 tonnes of CO2 per-capita, the same as Britain. This deal will mean that, at best, China’s emissions will peak above 10 tonnes of CO2 per-capita. This is higher than almost every developed economy. Higher than Germany, Japan, France, Britain. But still slightly lower than America.

In fact, what this deal seems to really be saying is that China and America’s per-capita CO2 emissions will converge sometime around 2030 at, say, 12 tonnes of CO2 per-capita.

China’s emissions, however, are not likely to do anything but plateau for decades after this peak. More or less all of its coal power plants have been built since 2000. It is therefore unlikely that China will be burning much less coal for electricity generation in the middle of the century. The same goes for coal used in steel making.

I think you are probably right. In the quick calculations above, I assumed China followed the A1B emissions path to 2030, which took them to about 6 tonnes of CO2 per capita – which, as you point out above, they have already exceeded. Running again with China reaching about 10 tonnes per capita by 2030 reduces the chance of staying below 2 degC in 2100 to about 0.3% – even if other countries respond to the US and China pledges as assumed in the 12:20 update above.

True,
Plus I would look at 10 tonnes per capita in 2030 as an optimistic number. This would be an increase of around 40% in 16 or so years. They increased by this percentage in the last 5 years.

A key issue here is that China’s personal consumption levels are still very low. Less than 7% of Chinese own cars, while per-capita household electricity consumption remains around a quarter of that in the UK. Industry has represented about 70% of China’s energy consumption more or less consistently each year since 2000.

A 50% increase in China’s energy consumption from now to 2030 is probably a lower estimate. However, China is now saying that low carbon will go from around 10% today to 20% by 2030. So, at best we are probably looking at a 40% or so increase in total fossil fuels.

The only thing that could probably stop a 40% increase in per-capita emissions, then, seems to be natural gas. Oil use is certain to rise significantly as China’s growing middle classes buy more and more cars. Shutting down coal power plants on large scale is almost certainly not going to happen. One possibility that perhaps gives hope is a push to replace direct use of coal in industry with natural gas. China uses over 700 million tonnes directly in industry. I suspect that capping China’s emissions at 25% of today’s level (as some have suggested the cap might be) would ultimately require a rapid transition from coal to gas an industrial feedstock. But this is not likely to be easy, given China’s lack of gas.

Hi Chris – many scenarios you could put into PAGE but what about Indonesia’s pledget to cut 2010 level of greenhouse gas emissions by as much as 26 to 41 percent by 2020. If emerging market follows them (or Mexico) does this make enough of a difference (essentially if the rest of the world goes on an ambitious mitigation drive does the China/US deal still mean we miss target by a large amount?).

[…] track to reduce pollution enough. Policy modeler Chris Hope of the University of Cambridge fed the new commitments plus the E.U. effort into a computer model under the assumption that other countries would continue to allow pollution to grow. He came out […]

[…] track to reduce pollution enough. Policy modeler Chris Hope of the University of Cambridge fed the new commitments plus the E.U. effort into a computer model under the assumption that other countries would continue to allow pollution to grow. He came out […]

[…] track to reduce pollution enough. Policy modeler Chris Hope of the University of Cambridge fed the new commitments plus the E.U. effort into a computer model under the assumption that other countries would continue to allow pollution to grow. He came out […]

A heartfelt thanks Chris for having the courage to raise your voice above the deafening silence of much of science community in pointing out very clearly that the China-US deal, combined with the EU’s 40% proposition, blows 2C out of the water. Given the tight carbon budgets in WGIII for a “likely” chance of 2C (630-1180GtCO2 for 2011-2100) – why is it that so many of us stay quiet when faced with such political rhetoric?

[…] a recent commitment by the European Union to cut its emissions by forty per cent before 2030. He found that even if all of the pledges made so far are fulfilled, there will be “less than a 1% chance […]

[…] more promising than they really were: The EU, US and China targets still put us on a road to a 3,8 °C warmer world, with the latest 5th Assessment Report of the IPCC warning of the imminent dangers of climate […]

[…] the two-degree barrier. Cambridge University professor and PAGE climate modeler Chris Hope, estimates that total commitments will give the world just a 1.1 percent chance of staying within two degrees […]

[…] Analysis by Chris Hope, running a PAGE09 integrated assessment model, takes the US and Chinese announcements, the EU’s pledge to cut emissions by 40% below 1990 by 2030; assumes the rest of the OECD matches the US’s actions of a 28% cut by 2025, and the rest of the developing world matches China’s pledge to stop increasing emissions by 2030. […]